Cable fitting having a clamping device for an armor of the cable

ABSTRACT

A cable gland including a screw sleeve which can be inserted into a wall or a pipe coupling is provided. A union nut interacts with the screw sleeve, and a clamping insert is acted on by the union nut and is adapted to be pressed against a cable which is to be retained by tightening the union nut. The cable has a reinforcement and a clamping device for clamping a portion of the reinforcement is provided in the cable gland. The clamping device partially engages in the screw sleeve in an axial direction in a use position and is acted on by the union nut outside the screw sleeve. A portion of the clamping device engages in the screw sleeve and acts in an interlocking manner on an inner face of the screw sleeve in the rotation direction in the use position.

BACKGROUND

The invention relates to a cable gland having a screw sleeve which canbe inserted into a wall or a pipe coupling, having a union nut whichinteracts with said screw sleeve, having a clamping insert which isacted on by the union nut and can be pressed against a cable which is tobe retained by tightening the union nut, wherein the cable has areinforcement means and a clamping device for clamping a portion of thereinforcement means is provided in the cable gland, said clamping devicepartially engaging in the screw sleeve in the axial direction in the useposition and being acted on by the union nut outside the screw sleeve.

A cable gland of this kind is known from DE 20 2005 014 138 U1 within aconstruction set and also from DE 692 18 853 T2. When the union nut istightened, the cable and its reinforcement means can be carried along inthe rotation direction in the process due to friction, and thereforeconnections of the cable within a housing can be damaged or destroyed.In order to solve this problem, pairs of tools which are intended toprevent twisting due to a high coefficient of friction have beenproposed or provided in practice in the region of the clamping device.However, when powerful clamping forces are exerted on the clampinginsert, it is nevertheless possible for the cable to be turned andtwisted when the union nut is being tightened, primarily when theclamping insert is just beginning to take effect.

SUMMARY

The object is therefore that of providing a cable gland of the kinddefined in the introductory part in which twisting of the cable while itis being clamped and while the reinforcement means of said cable isbeing clamped in can be avoided.

In order to achieve this object, the cable gland cited in theintroductory part is characterized in that that portion of the clampingdevice which engages in the screw sleeve acts in an interlocking manneron the inner face of the screw sleeve in the rotation direction in theuse position. This can prevent twisting of the clamping device or of thecable being clamped dependent on frictional forces and/or tool pairings.An interlocking connection in the rotation direction results, in anycase, in a considerably higher torque against twisting than can occur onthe cable when the union nut is tightened.

In this case, it is particularly expedient when the interlockingconnection, which acts in the rotation direction, is formed as a slidingor clamping fit in the axial direction. The clamping device cantherefore easily be pushed or inserted into the appropriate mating pieceof the screw sleeve by way of its interlocking region, withoutadditional measures for creating an interlocking connection in therotation direction being required. In this case, these parts, which canbe pushed together, could be provided with a conical design, but it isadvantageous for production purposes and also for assembly purposes forthose surfaces of the parts, which can be combined, which are matched inan interlocking manner in the rotation direction to be oriented parallelto the longitudinal center axis of the cable gland.

An expedient embodiment of the invention provides for the screw sleevein the engagement region of the clamping device and this clamping deviceto have, as a mutual rotation-prevention means, a matching non-roundcross section. Therefore, both the seat for the clamping device in thescrew sleeve and the region thereof which fits in this seat can be ofnon-round design in order to prevent twisting of these parts in relationto one another.

The non-round cross section can be realized in various ways. By way ofexample, it can be, at the screw sleeve and at the clamping device, across section which is flattened in regions, but otherwise a circularcross section, an elliptical or oval cross section or a profiled crosssection or a polygonal cross section or a cross section which hasprojections which are matched to one or more mating grooves, or atongue-and-groove connection can be provided between the screw sleeveand the clamping device.

It is particularly expedient for the non-round cross section for thecoupling, which is interlocking in the rotation direction and can beplug-connected in the axial direction, of the screw sleeve and of theclamping device to be a hexagon, a heptagon, an octagon or a decagon.Although a triangle, square or pentagon would be possible, the lower thewall thickness, primarily at the screw sleeve, the higher the number ofedges of the non-round cross section. The external cross section of thescrew sleeve can be correspondingly low in the region of this plugconnection.

An expedient and advantageous refinement of the invention for improvingfixing of the cable which belongs to the cable gland can involve thatend face of the clamping device which is located in the screw sleeve inthe use position acting on a second clamping insert which is arranged inthe screw sleeve and/or a seal by means of an oblique surface in such away that, when the clamping device is axially adjusted, the secondclamping insert and/or the seal can be pressed against the cable, inparticular against a region of the cable from which the insulation hasbeen stripped. In addition to a first clamping insert which canpreferably be pressed against the region of the cable from whichinsulation has not been stripped, a second clamping insert can thereforebe acted on with the aid of the clamping device, and therefore theclamping device has a double function since it firstly grasps thereinforcement means of the cable and secondly can contribute to furtherimproved clamping of the cable by means of a second clamping insertand/or a seal. In this case, the end face of the clamping device itselfcan have the corresponding oblique surface or the hollow cone or act ona pressure ring which is formed in such a way.

The clamping device can be in two parts and have a clamping body with aconical region which faces the union nut and have an axial clamping ringon this conical region, wherein, in the use position between the conicalregion and the clamping ring, parts of the reinforcement means, forexample reinforcement wires or a reinforcement film or foil, are fixedor clamped in. The clamping device can therefore correspondapproximately to those which are known from DE 20 2005 014 138 U1 andalso from DE 692 18 853 T2, this relating to the actual clamping region.

A further refinement of the invention can, on the basis of DE 20 2005014 138 U1, involve the union nut being divided and a first union nutserving to secure the clamping device, and the second union nut, whichis arranged coaxially to said first union nut, serving to act on thefirst clamping insert and/or a seal, wherein the first union nut has anexternal thread which is averted from the internal thread region of saidunion nut, and the second union nut has an internal thread which matchessaid external thread. The first union nut can therefore have the usualinternal thread for interacting with the external thread of the screwsleeve in its region which faces the screw sleeve, and, at a distancefrom said internal thread in the axial direction, have an externalthread for the internal thread of the additional union nut to act on.Therefore, the design and manner of operation can correspond to thecable gland according to DE 20 2005 014 138 U1.

In this case, it is expedient for a projection from the first or theonly union nut to act axially on the clamping device in the axialdirection so as to produce a clamping effect, in particular on thepressure ring, in the use position, as is likewise known from DE 20 2005014 138 U1 or from DE 692 18 853 T2. Tightening the union nut then notonly produces the clamping action of the clamping device itself, butalso acts axially on said clamping device in order to put into effect aclamping insert, which additionally interacts with it, on the cable.

An advantageous refinement and addition, in particular for securing theclamping device in the union nut by way of its non-round region, caninvolve the clamping device having, in its engagement region, acircumferential groove having a radially projecting, in particularelastic, retaining ring or O-ring, which engages in said circumferentialgroove, and the screw sleeve having, at its opening which faces theunion nut, an undercut which engages over the retaining ring or O-ringin the use position, preferably with an axial spacing. This producesadditional axial fixing of the clamping device, for example when theunion nut is loosened, as a result of which the situation of theclamping device also being loosened can be avoided. Instead, saidclamping device remains secured to the screw sleeve with the aid of theretaining ring when the union nut is loosened, wherein the retainingring can also contribute to twisting prevention, depending on thedimensions. In this case, the undercut could possibly also be formed byan annular groove which is arranged on the inside of the screw sleeveand accommodates the radial projecting portion of the retaining ring orO-ring in the use position.

It is particularly expedient for the undercut to delimit the non-roundinsertion region of the screw sleeve. In the case of an arrangement ofthis kind, the non-round cross section of the screw sleeve is thereforedelimited in the axial direction by an undercut, that is to say theaxial dimension of the non-round region of the screw sleeve is shorterthan the non-round region of the clamping body of the clamping device.When the clamping body and the screw sleeve are joined, the elasticretaining ring or O-ring can initially yield to a certain extent, untilthe non-round regions which are matched in an interlocking manner in therotation direction have attained their use position, as a result ofwhich the retaining ring or O-ring is then once again in the relaxedposition in the axial direction behind the undercut in the screw sleeveand secures this plug connection of the clamping device and the screwsleeve in the axial direction.

Primarily, combining individual or several of the above-describedfeatures and measures results in a cable gland having a pressure pieceon the clamping device, which pressure piece can be operated by a unionnut, by means of which this pressure piece, which is in the form of aclamping ring, can firmly clamp the cable reinforcement means and at thesame time can also axially secure the entire clamping device andpossibly can press said clamping device against a clamping insert,wherein this clamping device is prevented, by an interlocking connectionat its engagement point in the screw sleeve, from also rotating when oneor two union nuts are tightened.

BRIEF DESCRIPTION OF THE DRAWINGS

In the text which follows, exemplary embodiments of the invention aredescribed in greater detail with reference to the drawing, in which, insome cases schematically:

FIG. 1 shows a perspective view of a cable gland according to theinvention in exploded form, that is shortly before it is assembled,wherein the reinforcement means of the cable which is partially strippedof insulation is not yet connected to the associated clamping device andthis clamping device is not yet inserted into the associated screwsleeve by way of its polygonal region in a rotationally fixed manner,

FIG. 2 shows, on an enlarged scale, the detail which is marked by thedash-dotted circle in FIG. 1 with the polygonal part of the clampingdevice before it is inserted into the screw sleeve.

FIG. 3 shows, half in plan view and half in longitudinal section, thecable gland according to FIG. 1 before it is finally assembled, that isin an exploded illustration,

FIG. 4 shows, half in plan view and half in longitudinal section, thecable gland according to FIGS. 1 to 3 in the assembled position with thecable and its reinforcement means in the clamping position,

FIG. 5 shows an illustration which corresponds to FIG. 4 and in which asingle union nut is provided for acting on both a clamping insert andthe clamping device, said clamping device for its part, as in FIGS. 1 to4, acting on a second clamping insert,

FIG. 6 shows a cross section through the cable gland in the region ofthe rotationally fixed engagement point of the clamping device in thescrew sleeve, specifically without the cable, the clamping insert andthe union nut being illustrated, wherein the clamping device has anoctagonal cross section in its engagement region, said octagonal crosssection being fitted in an interlocking manner in a corresponding hollowcross section of the screw sleeve,

FIG. 7 shows an illustration which corresponds to FIG. 6, wherein anon-round cross section at that part of the clamping device whichengages in the screw sleeve is formed by two flattened portions of anotherwise circular cross section,

FIG. 8 shows an embodiment which corresponds to the illustration ofFIGS. 6 and 7 and in which the non-round cross section is oval orelliptical, and

FIG. 9 shows an illustration which corresponds to FIGS. 6 to 8, whereinthe non-round cross section is formed by projections, which are arrangedradially on a circular cross section, and matching mating grooves.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description of the exemplary embodiments, parts whichhave corresponding functions are provided with corresponding referencenumerals, even if their shape or design has been modified.

A cable gland, which is designated 1 overall, has a screw sleeve 2 whichcan be inserted into a wall or a pipe coupling or the like, at least oneunion nut 3 which interacts with said screw sleeve 2, and a firstclamping insert 5 which is acted on by the union nut and can be pressedagainst a cable 4 which is to be retained by tightening the union nut 3,and also a second clamping insert 6, wherein the cable 4 has areinforcement means 7, which is illustrated partially stripped ofinsulation in the figures, and a clamping device, which is designated 8overall, for clamping a portion, which is stripped of insulation, of thereinforcement means 7, is provided within the cable gland 1. Thisclamping device 8 partially engages in that open end of the screw sleeve2 which faces the union nut in the axial direction in the use positionand is acted on by the union nut 3 outside the screw sleeve 2 in theaxial and clamping direction.

In this case, two clamping inserts of differing dimensions, specificallythe larger first clamping insert 5 and the second, smaller clampinginsert 6 which is still to be described are provided in the twoexemplary embodiments, wherein the first, larger clamping insert 5 isacted on by a union nut 10 and the smaller, second clamping insert 6 isacted on by the union nut 3, while in the exemplary embodiment accordingto FIG. 5, a common union nut 3 acts on the screw sleeve 2 and bothclamping inserts 5 and 6 are acted on and clamped when said union nut istightened.

In order to ensure that the clamping device 8 cannot also rotate, andtherefore to prevent the reinforcement means 7 and/or the cable 4 fromalso rotating, when the union nut 3 is operated, that portion 8 a of theclamping device 8 which acts in the screw sleeve at the end face and theinner face of the screw sleeve 2 which is acted on by said portion inthe use position are formed in such a way that an interlockingconnection is established in the rotation direction in the assembledposition.

This interlocking connection which acts in the rotation direction, incontrast to in the axial direction, is in the form of a sliding fit,that is to say the clamping device 8 and, in particular, that portion 8a which engages in the screw sleeve 2 in the use position, can easily bepushed axially out of the position shown in FIGS. 1 and 2 into theposition shown in FIGS. 4 and 5, in order to then no longer be able totwist relative to the screw sleeve 2.

In this case, FIGS. 1 and 2 and primarily also FIGS. 6 to 9 particularlyclearly show that the screw sleeve 2 in the engagement region of theclamping device 8 and its portion 8 a and this clamping device 8 itselfon its portion 8 a have, as a mutual rotation-prevention means, amatching non-round cross section.

In this case, FIG. 7 shows that the non-round cross section at the screwsleeve 2 and at the clamping device 8 can have a cross section which isflattened in regions, in the exemplary embodiment is flattened twice,but otherwise is circular.

FIG. 8 shows, as a non-round cross section between the screw sleeve 2and the clamping device 8, an elliptical or oval cross section. In FIG.9, the matching cross sections which are fixed in the rotation directionare profiled, wherein a cross section which matches mating grooves 11 inthe screw sleeve 2 and has projections 12 is provided. Analogously, atongue-and-groove connection could also be provided, but the illustratedcross sections have the advantage that no additional tongue part isrequired.

FIG. 6 illustrates a preferred embodiment in which the non-round crosssection for the coupling, which is interlocking in the rotationdirection, of the screw sleeve 2 and the clamping device 8 or itsportion 8 a which engages in the screw sleeve 2 is an octagon, but couldalso be a hexagon, a heptagon or even a decagon. The greater the numberof edges, the thinner the walls of the screw sleeve 2 can be in theregion of this interlocking coupling, that is to say the smaller theexternal dimensions of the screw sleeve 2 can be in the coupling region.

If appropriate, so many edges or a profiling of this kind could alsoengage such that a tooth system could be produced.

In the two exemplary embodiments, provision is made for that end face ofthe clamping device 8 which is located in the screw sleeve 2 in the useposition, or of that portion 8 a of the clamping device 8 which engagesin the screw sleeve 2 to act on the second clamping insert 6, which isarranged in the screw sleeve 2, and a seal 13 in such a way that, whenthe clamping device 8 is axially adjusted by the union nut 3, the secondclamping insert 6 and the seal 13 can be pressed, and according to FIGS.4 and 5 is pressed, against the cable 4 in a region from which theinsulation has been stripped. It should be noted that the cable gland 1could, however, also function in an analogous manner if the secondclamping insert 6 and/or a seal 13 were not present. The only importantfactor is that the clamping device 8 finds an abutment in the axialdirection so that it can perform its clamping function, wherein thesecond clamping insert 6 is said abutment in the exemplary embodiments.

It can be seen, primarily in FIGS. 1 and 3 but also when looking atFIGS. 4 and 5 together, that the clamping device 8 is in two parts andhas a clamping body 14 which has the portion 8 a and has a conicalregion which faces the union nut 3 and has a clamping ring 15 which canbe axially adjusted to this conical region of the clamping body 14 andhas an internal cone, as is known from DE 20 2005 014 138 U1. In thiscase, portions of the reinforcement means 7, for example reinforcementwires or possibly even a reinforcement film or foil, are fixed orclamped in between the conical region and the clamping ring 15 when thecable gland 1 is assembled in the use position. In a manner known fromDE 20 2005 014 138 U1 the clamping device 8 is acted on and the clampingring 15 is pressed against the conical region of the clamping body 14 byvirtue of the union nut 3 being tightened, as a result of which contactis made with the reinforcement wires situated between said clamping ringand conical region and said reinforcement wires are secured. At the sametime, the clamping device 8 is secured in the axial direction andpressed against the second clamping insert 6, so that the oblique orconical end face 9 of the portion 8 a presses the clamping insert 6radially inward against the cable 4 in the manner illustrated in FIGS. 4and 5.

In the exemplary embodiment according to FIGS. 1 to 4, the union nut isdivided and the first union nut 3, which is situated closer to the screwsleeve 2 in the use position, serves to secure the clamping device 8,while the second union nut 10, which is arranged coaxially to said firstunion nut, serves to act on the first clamping insert 5 and a seal 16which is located there. In this case, the first union nut 3 has aninternal thread in its region which engages over the union nut 2 andwhich matches the external thread of the screw sleeve 2, while it alsohas an external thread 3 a on its opposite end region, an internalthread of the second union nut 10 matching said external thread, so thatthe two union nuts 3 and 10 can be screwed together in the mannerillustrated in FIG. 4 in order to exert their respective action.

In this case, in the exemplary embodiment according of FIGS. 1 to 4, thefirst union nut 3 has a pressure ring 17 which is integrally connectedto said union nut and acts in the axial direction so as to produce theclamping action.

In the exemplary embodiment according to FIG. 5, however, a separatepressure ring 18 is provided, said pressure ring being axially acted onby the common union nut 3 by means of the clamping insert 5, in order tooperate the clamping device 8.

In this case, FIGS. 3 and 4 illustrate a way of securing the clampingdevice 8 in the axial direction in its use position, so that it cannotunintentionally fall out of the screw sleeve 2 again when the union nut3 is loosened. To this end, provision is made for the clamping device 8to have, in its engagement region, a circumferential groove having aradially projecting, preferably elastic, retaining ring or O-ring 19,which engages in said circumferential groove, and the screw sleeve 2having, at its opening which faces the union nut 3, an undercut 20 whichengages over the retaining ring or O-ring 19 in the use positionaccording to FIG. 4 with an axial spacing. In this case, the undercut 20is formed by a widening in the cross section being provided in the axialdirection adjacent to the non-round region of the union nut 3, saidwidening being somewhat recessed in relation to the non-round crosssection of the screw sleeve 2 in the radial direction. The undercut 20therefore delimits the non-round insertion region of the screw sleeve 3on the inside, and therefore the retaining ring or O-ring 19 assumes itsposition in which it is relaxed in the radial direction behind saidundercut 20 in the insertion direction, as is illustrated in FIG. 4.

The illustrations according to FIGS. 1 and 5 show that the cable glandcan, however, also be designed without a retaining ring or O-ring 19 ofthis kind.

The cable gland 1 has a screw sleeve 2 which can be inserted into a wallor a pipe coupling and has an external thread, and has a union nut 3which interacts with said external thread of the screw sleeve 2. Theunion nut 3 can be used, by virtue of being tightened, to press aclamping insert 5 against a cable 4 which is to be retained, wherein thecable 4 has a reinforcement means 7 which is exposed at least at pointsor is free within the cable gland 1. A clamping device 8 for clamping aportion of this reinforcement means 7 is provided in the cable gland 1,said clamping device 8 partially engaging in the inner opening in thescrew sleeve 2 in the axial direction in the use position and beingdirectly or indirectly acted on by the union nut 3 outside the screwsleeve 2. In order to prevent twisting of the cable 4 and/or theclamping device 8 when the union nut 3 is tightened, that portion 8 a ofthe clamping device 8 which engages in the screw sleeve 2 is secured inan interlocking manner on the inner face of the screw sleeve 2 in therotation direction in the use position and has, for example, a polygonalcross section. In this case, the clamping device 8 can, by way of itsend face 9 which engages in the screw sleeve 2, act on a second clampinginsert 6.

The invention claimed is:
 1. A cable gland (1) comprising: a screwsleeve (2) which is insertable into a wall or a pipe coupling, a unionnut (3) which interacts with said screw sleeve (2), the screw sleeve (2)including an opening which faces the union nut (3), a clamping insert(5, 6) which is acted on by the union nut (3) and is adapted to bepressed against a cable (4) which is to be retained by tightening theunion nut (3), wherein the cable (4) has a reinforcement (7), and aclamping device (8) for clamping a portion of the reinforcement (7) isprovided in the cable gland (1), said clamping device (8) partiallyengaging in the screw sleeve (2) in an axial direction in a use positionand being acted on by the union nut (3) outside the screw sleeve (2),and an engagement portion (8 a) of the clamping device (8) which engagesin the screw sleeve (2) at an engagement region of the screw sleeve (2)acts in an interlocking connection on an inner face of the screw sleeve(2) in a rotation direction in the use position, wherein the screwsleeve (2) in the engagement region and the clamping device (8) in theengagement portion (8 a) have matching non-round cross sections, and theclamping device (8) has, in the engagement portion (8 a), acircumferential groove having a radially projecting retaining ring orO-ring (19), which engages in said circumferential groove, and the screwsleeve (2) has, at the opening facing the union nut (3), an undercut(20) which engages over the retaining ring or O-ring (19) in the useposition.
 2. The cable gland as claimed in claim 1, wherein theinterlocking connection, which acts in the rotation direction, betweenthe clamping device (8) and the screw sleeve (2) is provided with asliding or clamping fit in the axial direction.
 3. The cable gland asclaimed in claim 1, wherein the non-round cross sections are flattenedin regions, but otherwise have a circular cross section, an ellipticalor oval cross section or a profiled cross section or a polygonal crosssection or a cross section which has projections (12) which are matchedto one or more mating grooves (11), or a tongue-and-groove connection isprovided between the screw sleeve (2) and the clamping device (8). 4.The cable gland as claimed in claim 1, wherein the non-round crosssections for the coupling, which are interlocking in the rotationdirection, of the screw sleeve (2) and of the clamping device (8) are ahexagon, a heptagon, an octagon, or a decagon.
 5. The cable gland asclaimed in claim 1, wherein an end face (9) of the clamping device (8)which is located in the screw sleeve (2) in the use position acts on atleast one of a second clamping insert (6) which is arranged in the screwsleeve (2) or a seal (13) by an oblique surface in such a way that, whenthe clamping device (8) is axially adjusted, the at least one of secondclamping insert (6) or the seal (13) is pressed against the cable. 6.The cable gland as claimed in claim 1, wherein the clamping device (8)is in two parts and has a clamping body (14) with a conical region whichfaces the union nut (3) and has a clamping ring (15) which is axiallyadjustable on the conical region, and in the use position between theconical region and the clamping ring (15), parts of the reinforcement(7) are adapted to be fixed or clamped in.
 7. The cable gland as claimedin claim 1, wherein the union nut is divided and a first union nut (3)serves to secure the clamping device (8), and a second union nut (10),which is arranged coaxially to said first union nut, serves to act on atleast one of the first clamping insert (5) or a seal (16), and the firstunion nut (3) has an external thread (3 a), and the second union nut(10) has an internal thread which matches said external thread.
 8. Thecable gland as claimed in claim 7, wherein a projection (17) from thefirst or only union nut (3) acts axially on the clamping device (8) inthe axial direction so as to produce a clamping effect in the useposition.
 9. The cable gland as claimed in claim 1, wherein theretaining ring or O-ring (19) is elastic.
 10. The cable gland as claimedin claim 9, wherein the undercut (20) engages over the retaining ring orO-ring (19) in the use position with an axial spacing.
 11. The cablegland as claimed in claim 1, wherein the undercut (20) delimits thenon-round insertion region of the screw sleeve (2) in the axialdirection.